package modules

import (
	"bytes"
	"context"
	"os"
	"time"

	"github.com/ipfs/go-bitswap"
	"github.com/ipfs/go-bitswap/network"
	"github.com/ipfs/go-blockservice"
	"github.com/ipfs/go-datastore"
	"github.com/ipld/go-car"
	"github.com/libp2p/go-libp2p-core/host"
	"github.com/libp2p/go-libp2p-core/routing"
	pubsub "github.com/libp2p/go-libp2p-pubsub"
	"go.uber.org/fx"
	"golang.org/x/xerrors"

	"github.com/filecoin-project/lotus/extern/sector-storage/ffiwrapper"
	"github.com/filecoin-project/lotus/journal"

	"github.com/filecoin-project/lotus/build"
	"github.com/filecoin-project/lotus/chain"
	"github.com/filecoin-project/lotus/chain/beacon"
	"github.com/filecoin-project/lotus/chain/exchange"
	"github.com/filecoin-project/lotus/chain/gen/slashfilter"
	"github.com/filecoin-project/lotus/chain/messagepool"
	"github.com/filecoin-project/lotus/chain/stmgr"
	"github.com/filecoin-project/lotus/chain/store"
	"github.com/filecoin-project/lotus/chain/types"
	"github.com/filecoin-project/lotus/chain/vm"
	"github.com/filecoin-project/lotus/lib/blockstore"
	"github.com/filecoin-project/lotus/lib/bufbstore"
	"github.com/filecoin-project/lotus/lib/timedbs"
	"github.com/filecoin-project/lotus/node/modules/dtypes"
	"github.com/filecoin-project/lotus/node/modules/helpers"
	"github.com/filecoin-project/lotus/node/repo"
)

func ChainBitswap(mctx helpers.MetricsCtx, lc fx.Lifecycle, host host.Host, rt routing.Routing, bs dtypes.ChainBlockstore) dtypes.ChainBitswap {
	// prefix protocol for chain bitswap
	// (so bitswap uses /chain/ipfs/bitswap/1.0.0 internally for chain sync stuff)
	bitswapNetwork := network.NewFromIpfsHost(host, rt, network.Prefix("/chain"))
	bitswapOptions := []bitswap.Option{bitswap.ProvideEnabled(false)}

	// Write all incoming bitswap blocks into a temporary blockstore for two
	// block times. If they validate, they'll be persisted later.
	cache := timedbs.NewTimedCacheBS(2 * time.Duration(build.BlockDelaySecs) * time.Second)
	lc.Append(fx.Hook{OnStop: cache.Stop, OnStart: cache.Start})

	bitswapBs := bufbstore.NewTieredBstore(bs, cache)

	// Use just exch.Close(), closing the context is not needed
	exch := bitswap.New(mctx, bitswapNetwork, bitswapBs, bitswapOptions...)
	lc.Append(fx.Hook{
		OnStop: func(ctx context.Context) error {
			return exch.Close()
		},
	})

	return exch
}

func MessagePool(lc fx.Lifecycle, sm *stmgr.StateManager, ps *pubsub.PubSub, ds dtypes.MetadataDS, nn dtypes.NetworkName, j journal.Journal) (*messagepool.MessagePool, error) {
	mpp := messagepool.NewProvider(sm, ps)
	mp, err := messagepool.New(mpp, ds, nn, j)
	if err != nil {
		return nil, xerrors.Errorf("constructing mpool: %w", err)
	}
	lc.Append(fx.Hook{
		OnStop: func(_ context.Context) error {
			return mp.Close()
		},
	})
	return mp, nil
}

func ChainRawBlockstore(lc fx.Lifecycle, mctx helpers.MetricsCtx, r repo.LockedRepo) (dtypes.ChainRawBlockstore, error) {
	bs, err := r.Blockstore(helpers.LifecycleCtx(mctx, lc), repo.BlockstoreChain)
	if err != nil {
		return nil, err
	}

	// TODO potentially replace this cached blockstore by a CBOR cache.
	cbs, err := blockstore.CachedBlockstore(helpers.LifecycleCtx(mctx, lc), bs, blockstore.DefaultCacheOpts())
	if err != nil {
		return nil, err
	}

	return cbs, nil
}

func ChainBlockService(bs dtypes.ChainRawBlockstore, rem dtypes.ChainBitswap) dtypes.ChainBlockService {
	return blockservice.New(bs, rem)
}

func FallbackChainBlockstore(rbs dtypes.ChainRawBlockstore) dtypes.ChainBlockstore {
	return &blockstore.FallbackStore{
		Blockstore: rbs,
	}
}

func SetupFallbackBlockstore(cbs dtypes.ChainBlockstore, rem dtypes.ChainBitswap) error {
	fbs, ok := cbs.(*blockstore.FallbackStore)
	if !ok {
		return xerrors.Errorf("expected a FallbackStore")
	}

	fbs.SetFallback(rem.GetBlock)
	return nil
}

func ChainStore(lc fx.Lifecycle, bs dtypes.ChainBlockstore, lbs dtypes.ChainRawBlockstore, ds dtypes.MetadataDS, syscalls vm.SyscallBuilder, j journal.Journal) *store.ChainStore {
	chain := store.NewChainStore(bs, lbs, ds, syscalls, j)

	if err := chain.Load(); err != nil {
		log.Warnf("loading chain state from disk: %s", err)
	}

	lc.Append(fx.Hook{
		OnStop: func(_ context.Context) error {
			return chain.Close()
		},
	})

	return chain
}

func ErrorGenesis() Genesis {
	return func() (header *types.BlockHeader, e error) {
		return nil, xerrors.New("No genesis block provided, provide the file with 'lotus daemon --genesis=[genesis file]'")
	}
}

func LoadGenesis(genBytes []byte) func(dtypes.ChainBlockstore) Genesis {
	return func(bs dtypes.ChainBlockstore) Genesis {
		return func() (header *types.BlockHeader, e error) {
			c, err := car.LoadCar(bs, bytes.NewReader(genBytes))
			if err != nil {
				return nil, xerrors.Errorf("loading genesis car file failed: %w", err)
			}
			if len(c.Roots) != 1 {
				return nil, xerrors.New("expected genesis file to have one root")
			}
			root, err := bs.Get(c.Roots[0])
			if err != nil {
				return nil, err
			}

			h, err := types.DecodeBlock(root.RawData())
			if err != nil {
				return nil, xerrors.Errorf("decoding block failed: %w", err)
			}
			return h, nil
		}
	}
}

func DoSetGenesis(_ dtypes.AfterGenesisSet) {}

func SetGenesis(cs *store.ChainStore, g Genesis) (dtypes.AfterGenesisSet, error) {
	genFromRepo, err := cs.GetGenesis()
	if err == nil {
		if os.Getenv("LOTUS_SKIP_GENESIS_CHECK") != "_yes_" {
			expectedGenesis, err := g()
			if err != nil {
				return dtypes.AfterGenesisSet{}, xerrors.Errorf("getting expected genesis failed: %w", err)
			}

			if genFromRepo.Cid() != expectedGenesis.Cid() {
				return dtypes.AfterGenesisSet{}, xerrors.Errorf("genesis in the repo is not the one expected by this version of Lotus!")
			}
		}
		return dtypes.AfterGenesisSet{}, nil // already set, noop
	}
	if err != datastore.ErrNotFound {
		return dtypes.AfterGenesisSet{}, xerrors.Errorf("getting genesis block failed: %w", err)
	}

	genesis, err := g()
	if err != nil {
		return dtypes.AfterGenesisSet{}, xerrors.Errorf("genesis func failed: %w", err)
	}

	return dtypes.AfterGenesisSet{}, cs.SetGenesis(genesis)
}

func NetworkName(mctx helpers.MetricsCtx, lc fx.Lifecycle, cs *store.ChainStore, us stmgr.UpgradeSchedule, _ dtypes.AfterGenesisSet) (dtypes.NetworkName, error) {
	if !build.Devnet {
		return "testnetnet", nil
	}

	ctx := helpers.LifecycleCtx(mctx, lc)

	sm, err := stmgr.NewStateManagerWithUpgradeSchedule(cs, us)
	if err != nil {
		return "", err
	}

	netName, err := stmgr.GetNetworkName(ctx, sm, cs.GetHeaviestTipSet().ParentState())
	return netName, err
}

type SyncerParams struct {
	fx.In

	Lifecycle    fx.Lifecycle
	MetadataDS   dtypes.MetadataDS
	StateManager *stmgr.StateManager
	ChainXchg    exchange.Client
	SyncMgrCtor  chain.SyncManagerCtor
	Host         host.Host
	Beacon       beacon.Schedule
	Verifier     ffiwrapper.Verifier
}

func NewSyncer(params SyncerParams) (*chain.Syncer, error) {
	var (
		lc     = params.Lifecycle
		ds     = params.MetadataDS
		sm     = params.StateManager
		ex     = params.ChainXchg
		smCtor = params.SyncMgrCtor
		h      = params.Host
		b      = params.Beacon
		v      = params.Verifier
	)
	syncer, err := chain.NewSyncer(ds, sm, ex, smCtor, h.ConnManager(), h.ID(), b, v)
	if err != nil {
		return nil, err
	}

	lc.Append(fx.Hook{
		OnStart: func(_ context.Context) error {
			syncer.Start()
			return nil
		},
		OnStop: func(_ context.Context) error {
			syncer.Stop()
			return nil
		},
	})
	return syncer, nil
}

func NewSlashFilter(ds dtypes.MetadataDS) *slashfilter.SlashFilter {
	return slashfilter.New(ds)
}
